Detinning.



UNITED STATES I PA ENT osnron;

RAYMOND s. WILE,'OE PITTSBURGfPENNsY VniiIA.

' msrmnmo. I

provement in Detinning,.of which improvement the following is a specification.

The invention described herein relates to certain improvements in the removal of .tin from t-in plate and its recovery and reductidn to merchantable form.

The invention is hereinafter more fully described I and claimed.

I in the practice of my invention the tin plate usually in the form of scrap is subjected to the action of stannic chlorid whereby the tin is dissolved from the iron or steel, which is no t acted on to any material extent by the stannic chlorid. The tin taken up by the stannic chlorid (producing stannous 'chlorid) is removed from the solution bysuitable treatment, whereby the tin rev covered assumes a crystalline form.

While not limiting the invention to any particular strength of stannic chlorid solution, it should have 'a strength sufiicientto take up a maximum amount of tin without, materially attacking the iron or steel. These conditions seem to be filled by fifteen to twentyfive per cent solutionsan "approximately twenty per cent (20%) solution giving the best results. The tin plate is pla'cedin this solution, which is agitated was to facilitate the removal of the tin. An apparatus such as is used in pickling sheet iron or steel can be conveniently usedin carrying out my process. An addition of hydrochloricacid to the solution inereases the efficiency of the process, not only during thesolution of the tin butalso while the latter is being separated from the solution where the solution is reconvcrted: to stanhic chlorid. J

To remove the tin from the solution, the latter is subjected to treatmenh as the action of an electric current,

' chlorid, the efliciency of the process is increased. .by-

adding the hydrochloric acid before or during the dis- 7 Specification of Letters Patent; Application filed O tober 19,1906. stratu 339.596.

Patented r ly-9,1907.

the best results are obtained by adding from -fivetenths to five per cent of hydrochloric acid. After the tin has been removed, the starinous chlorid thus produced is subjectedto electrolytic/action;the solution being preferably transferred to a number of small vats in order to hasten the removal of the tin. The anode em loyed should be formed of some material as carbon,

insoluble in the bath. By the action of the current, which preferably is about four volts and a current strength of about one ampere per square inch of cathode, the tin taken upby the solution is deposited on the cathode in the form ofsilvery white crystals.

As soon as the solution has been reconyerted to stan-v -nic chlorid by the removal of the tin, the electrolytic treatment is stopped and tl'lO SOllltlOIl returned to the pickling bath, for the treatment of another quanti tyof tinplate. I

After the solution has becomeunfit for use in my process, it is mingled with a large-quantity of pure water, win-ruby the tin eontained in the solution is precipitated in the form oistaunic oxid, a commercially valuable product. f By the addition of hydrochloric acid the removal of the tin from the plate is materially hastened, but the greatest benefit is derived in maintaining the crystalline character of the deposit during the electrolytic treatment. n

I claim herein as my invention:

1.'The-herein described process of detinnlng, which consists in dissolving the tin in a solution and subjecting such solution totheactlon of a current 'of sufficient voltage'to cause theseparntion of the tin, said solution consisting of stannic thereto. 7

2. The herein described process of Ge-tinnlng which consists in dissolving the tin in-a solution of stannic chlorid producing stannous chlorid, adding hydrochloric acid to the latter, and separating the .tin from the stannous chlorid' by the action of a current of suificient voltage to cause the tin to assume on separation a crystalline form.

3. The hereln'descrlbed process of de-tinning which consists in dissolving the tin in a solution of stannig chlnrid having at least a fifteen per cent concentration, thereby producing stannous chlorld, adding hydrochloric acid and separating the tin from thencid solution by the action oi. an electric current of suflicien't voltage to cause the tin to v assume-a crystalline form.

4.-The herein described process of de-tinning, whichconsists in changing; a solutlon'of stannic chlorid having at least a fifteen per cent concentration and containing hydrochioric acid, ton mlxture'of stannous chlo'rld and by:

.droclilorlc acid by the addition of tin to the first mixture and then subjecting such solution to the action of a current oi. suflielent voltage to cause the separation ot'tiu in a crystalline form, thereby restoringthe bath to its orlginal condition."

5. The herein described process of chlorid having hydro chloric added 85 1 2 g a smm a I consist'sln dissolving tin in a solution of stannic chlo'rid acid added thereto; removing the tin by electrolytic action, 10

having. at least a fli'teen per cent co'mentration, thereby and mingling the solution, after the electrolytic removal hydrochloric-acid added thereto, and then removing the of the tin with water. whereby stannic oxid is precipi- .tinfrom such solution by the action oi. a current of sum tated.

cient voltage to cruise the'separatlon of the tin in a crystal- In testimony whereof, I have hereunto set my hand. line form; I RAYMOND S. WIDE.

6. The process hereindescribed, which consists in dis- Witnesses: solving tin in a solution of stannie chlorid having at least 'Cmmmzs BARNETT,

a fifteen per centconcent'ratlon and having hydrochlorle J. HERBERT BRADLEY. 

